417
FXUS63 KLSX 291037
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
437 AM CST Thu Jan 29 2026

.KEY MESSAGES...

- Banded snow is likely this afternoon into tonight. Isolated 1-2" of
  snow is possible within the band with little to no
  accumulations expected outside of its track.

- Brutal cold is expected again this weekend. Wind chill values of
  -10 to -15 degrees are possible Saturday morning.

- An active pattern with multiple chances of precipitation is
  expected Sunday through at least midweek.


&&

.SHORT TERM...  (Through Late Friday Afternoon)
Issued at 325 AM CST Thu Jan 29 2026

The focus for today is the potential for accumulating snow and
potential freezing drizzle in the area. Though the chance of light
snow will begin as early afternoon as the system enters northeast
Missouri, the best chance for accumulating snow won`t occur until
later in the afternoon and into the evening as warm air advection
and mid-level frontogenesis are maximized. This is forecast to
result in a narrow band of snow with a greater chance of actual
accumulations. 1-2" on the table at the most. SLRs are expected to
be higher than 10:1 given the cold with even higher SLRs in the
heart of the band. Outside of the band`s track, totals will be slim
to none. However, anything that does fall will stick and slick spots
on roads will be possible anywhere that sees snow. Where exactly the
snow band will gain its footing and track is still uncertain, but
models have been trending toward laying the band over I-70 in the
early evening before it heads south. The latest CAMs don`t really
reflect this, and are unsure if the band will be impacting
Louisiana, MO or Valles Mill, MO or if it`ll even exist at all at
that time. Seeing that we`re confident in the existence of a
mesoscale band forming based on experience and the suite of guidance
at our disposal, current PoPs reflect the most likely scenario in
our eyes and do not necessarily align well with any one model.

Signals for freezing drizzle are present in the Ozarks and southern
Illinois this afternoon, but the potential for impactful ice
accumulations is slim due to short duration and very low QPF (20-50%
chance) of 0.01"/6 hours. Confidence is increasing in a seeder-
feeder set-up cutting drizzle off after a couple of hours as ice
crystals from the mid-levels fall into the saturated low-levels. The
aforementioned band will then pass through the Ozarks and may still
be able to produce light accumulations before exiting the CWA to the
south.

There is a potential for light snow showers across the area Friday
afternoon with the passage of another shortwave. Sounding data
supports this possibility as multiple models show very steep low-
level lapse rates with even a morsel of instability near the top of
the boundary layer. However, the chance of 6 hour QPF Friday
afternoon reaching 0.01" is still near 0% amongst ensembles, so left
the forecast dry.

An anomalously strong 1040-1045+ mb surface high will begin to spill
Arctic air into the Mid-Mississippi Valley on Friday. Lows Friday
morning will enter the 0 - 10 degree range again with wind chills 10
degrees cooler, and highs for most will only climb into the teens.

Jaja

&&

.LONG TERM...  (Friday Night through Wednesday)
Issued at 325 AM CST Thu Jan 29 2026

The cold will only strength Friday into Saturday as the surface high
and airmass overtake the region. Currently Saturday morning is
forecast to be our coldest. The cold air will be closer then, but
the surface high will still be far enough away to keep winds
slightly elevated. This combination is forecast to create
dangerously cold wind chills on the scale of -10 to -15 degrees.
Sunday morning will be nearly equally as cold in terms of air
temperature, but the much closer surface high will dampen surface
winds and wind chills will not be as brutal as a result.

Our next chance of snow is late Sunday, but uncertainties are still
plentiful. Ensemble guidance are still acting very
deterministically, producing drastic either/or situations. Where the
ECMWF depicts a 90%+ chance of snow, the GEFS gives less than
10%. Despite increasing confidence in a warming trend beginning
Sunday, temperatures will still likely be cool enough to produce
all snow if we do see any that day. Ironically, ensembles are in
much better agreement in another chance of precipitation occurring
sometime in the Tuesday/Wednesday time frame. Precipitation type
will be dictated by the degree of warming we see next week, which
is still quite uncertain given the 10+ degree spread between the
NBM 25th and 75th percentile high temperatures next week.

Jaja

&&

.AVIATION...  (For the 12z TAFs through 12z Friday Morning)
Issued at 407 AM CST Thu Jan 29 2026

VFR conditions are forecast for much of the area through the TAF
period. Light snow is expected today across much of the area, but
accumulations will be slim to none. The exception to this will be
within a narrow band where isolated 1-2" may accumulate. This band
is forecast to strength near I-70 and move south through the
evening between ~23z - 08z. MVFR clouds will build in south of
I-70 tonight as well, but confidence isn`t high in how far north
it gets. For this reason, left SCT MVFR with VFR ceilings in the
TAFs from COU/STL and south. Finally, light and variable winds
this morning will increase slightly from the northeast before
lightening up and backing to northerly tonight.

Jaja

&&

.LSX WATCHES/WARNINGS/ADVISORIES...
MO...None.
IL...None.
&&

$$

WFO LSX